Generally, infrared (IR) spectroscopy (which is broadly defined herein to include, but is not necessarily limited: to near-infrared (NIR), mid-infrared (MIR), and far-infrared (FIR)) is based on molecular vibration and rotation modes, as well as combination and overtone bands. Because molar absorptivity in the near-infrared (NIR) region of the electromagnetic spectrum can be quite small, NIR radiation can typically penetrate quite far into a sample (e.g., as compared to mid-infrared (MIR) radiation). Thus, IR spectroscopy techniques, such as diffuse reflectance NIR spectroscopy and Fourier transform infrared spectroscopy (FTIR), can be useful for probing bulk material. Further, NIR spectroscopy generally requires limited or no sample preparation. Near-infrared spectroscopy (NIRS) can be used in materials characterization and molecular analysis applications as diverse as pharmaceuticals, medical diagnostics, neurology, neuroimaging, neonatal research, urology, food and agrochemical quality control, combustion product analysis, sports medicine, sports science, sports training, ergonomics, rehabilitation, and so forth.